I've scanned through the thread and would have one point to add regarding some of the Old Testament Laws that were mentioned in Leviticus and Deuteronomy.
As has been mentioned already, Jesus' life and teachings put the Old Law to rest so to speak. I think the bottom line of the Old Testament is that over and over again God's people turned their back on him and he continues to accept them back.
Anyways, back to my point, many Biblical scholars will point out that many of the Old Testament Laws would have also been seen as sanitary precautions for the Jewish people. These weren't just "spiritual laws" but laws that governed a nation, much like we have speed limits, etc today.
Think about a couple of these things: - Would tattoos have been a sanitary thing at that point for the Jewish nation? (I'm not always convinced that tattoo parlors are safe today). - Would eating red meat have been a good idea without proper cooking procedures?